Lumajang Regency is a Regency (kabupaten) located in the East Java province of Indonesia. It covers an area of 1,790.90 sq. km, and had a population of 1,006,458 at the 2010 Census and 1,119,251 at the 2020 Census. The mid 2022 official estimate was originally stated to be 1,137,230, but was revised down to 1,097,504. The official estimate for mid 2023 was 1,108,487 (comprising 550,172 males and 558,315 females). The regency shares its land borders with Jember Regency (to the east), Probolinggo Regency (to the north), and Malang Regency (to the west), while it borders the Indian Ocean to the south.

Lumajang is located approximately 150 km southeast of Surabaya. Its temperature ranges between 24 °C to 32 °C.

Lumajang is one of the ancient cities in Java which still exist up to this day. According to Mula Malurung artifact (dated 1177 Saka), Lumajang was then ruled by King Nararyya Kirana Sminingrat. The date of the artifact, which is 15 December 1255 in the Gregorian calendar, was decided as the date of establishment of Lumajang. Menhirs found in the districts of Senduro, Gucialit, Sukodono, Klakah, and Lumajang reveal that in prehistoric times, the present area of Lumajang had already been inhabited long before the date of Mula Malurung artifact.

For legislators elected in 2024, the regency is represented in the national and provincial houses of representatives as part of East Java's 4th electoral district [id] and the provincial 5th electoral district, respectively, both of which it shares with neighboring Jember Regency. The municipal legislature [id] has 50 members elected from 7 electoral districts. The current acting regent, serving since 24 September 2023, is Indah Wahyuni, who replaced the previously elected regent Thoriqul Haq.

Lumajang Regency is divided into 21 districts (kecamatan), tabulated below with their areas and their populations at the 2010 Census and the 2020 Census, together with the official estimates as at mid 2023. Each district bears the same name as its administrative centre. The table also includes the numbers of administrative villages in each district (totalling 198 rural desa and 7 urban kelurahan - the latter all in Lumajang (town) District), and the post codes.

Kode Wilayah	Name of District (kecamatan)	Area in km	Pop'n Census 2010	Pop'n Census 2020	Pop'n Estimate mid 2023	No. of villages	Post code
35.08.01	Tempursari	105.35	28,501	33,819	33,687	7	67375
35.08.02	Pronojiwo	141.49	31,737	37,759	36,034	6	67374
35.08.03	Candipuro	143.09	62,226	73,617	75,354	10	67373
35.08.04	Pasirian	128.39	83,683	92,035	90,047	11	67372
35.08.05	Tempeh	73.21	78,806	85,929	84,751	13	67371
35.08.10	Lumajang (town)	28.47	80,685	84,649	84,772	12	67316
35.08.21	Sumbersuko	29.07	33,913	36,137	36,571	8	67316
35.08.09	Tekung	27.88	32,565	35,565	35,477	8	67381
35.08.06	Kunir	53.30	51,679	56,181	56,094	11	67383
35.08.07	Yosowilangun	72.44	56,546	61,299	60,411	12	67382
35.08.08	Rowokangkung	58.88	34,149	38,391	38,200	7	67359
35.08.17	Jatiroto	53.69	45,247	48,226	47,643	6	67355
35.08.18	Randuagung	93.92	60,853	70,343	69,375	12	67354
35.08.15	Sukodono	28.81	49,949	56,352	56,382	10	67351
35.08.14	Padang	53.83	34,615	37,943	37,586	9	67352
35.08.11	Pasrujambe	162.47	34,916	40,987	41,111	7	67361
35.08.12	Senduro	170.90	42,892	49,314	50,032	12	67362
35.08.13	Gucialit	101.79	23,436	26,274	26,041	9	67353
35.08.16	Kedungjajang	66.13	43,499	47,685	46,388	12	67358
35.08.19	Klakah	87.42	51,118	56,664	54,593	12	67356
35.08.20	Ranuyoso	110.36	45,443	50,082	47,938	11	67357
	Totals	1,790.90	1,006,458	1,119,251	1,108,487	205

Notes: (a) comprising 7 urban kelurahan (Citrodiwangsan, Ditotrunan, Jogotrunan, Jogoyudan, Kepuharjo, Rogotrunan and Tompokerasan) and 5 rural desa.
(b) except the kelurahan of Tompokersan (postcode 67311), Citrodiwangsan (67312), Ditotrunan (67313), Jogotrunan (67314) and Jogoyudan (67315);
the other kelurahan of Kepuharjo and Rogotrunan share the 67316 postcode with the 5 desa within Lumajang District and the whole of Sumbersuko District.

The population comprises Javanese, Madurese, Chinese Indonesians, and Tenggerese.

Lumajang has a tropical savanna climate (Aw) with moderate to little rainfall from May to September and heavy to very heavy rainfall from October to April.

• Agrowisata Royal Family (agro, fruit picking centers, outbound, and family vacation spot)
• Selokambang—a natural swimming pool
• The Triangle Lake, which consists of three crater lakes (Ranu Klakah, Ranu Bedali, Ranu Pakis)
• Ranu Pane, Ranu Regulo, Ranu Kumbolo—crater lakes at the slope of Mount Semeru
• Mount Semeru
• Tetes Cave
• Mandara Giri Temple
• Piket Nol (highway place where we can see Cold Lava from Semeru)
• Tumpak Sewu Waterfalls

• (in Indonesian) Official website
• Tourism site

8°08′S 113°13′E / 8.133°S 113.217°E / -8.133; 113.217